1906] HASSELBRING—APPRESSORIA OF ANTHRACNOSES 137 
organs of Gloeosporium. CLINTON'' regards them as chlamyd- 
ospores, They are also briefly described by Von SCHRENK and 
SPAULDING"? who add Gloeos porium cactorum to the list of anthrac- 
noses producing them. In order to clear up the uncertainty 
expressed in the literature regarding these organs, the following 
experiments and observations on the appressoria of Gloeosporium 
jructigenum are here recorded. 
FORMATION OF APPRESSORIA. 
As has been said, DE Bary and BiscEen have shown that the 
stimulus of mechanical contact is the cause of the formation of 
adhesion organs. Regarding the adhesion organs of Gloeosporium 
Miss SourHWorTH mentions the fact that they are especially 
numerous where a hypha comes into contact with some hard object 
like the cover glass. Hatsrep finds that a rich nutrient medium 
produces only a meager supply of “special cells,” while pure water 
increases their production. In neither case were these suggestions 
further investigated. Other writers had suggested in a general 
way that “unfavorable conditions” and starvation of mycelium 
Cause the formation of the special cells. 
Spores were sown in convex drops of water on slides kept in a 
moist chamber. Under these conditions the spores germinate 
Tapidly, but their behavior varies 
according to their position in the 
drops. Those which sink to the 
bottom of the drop form a short 
germ tube, which enlarges into a 
found or pear- shaped disc when 
: comes into contact with the 
ass, : 
hs developed into complete adhe, ctv med 
sign Orpan ie. i hk P: " germinating in water on glass slides. 
-is a brown 
Spore-like body, having a thick wall which is perforated on its lower 
appressed surface with a very distinct germ pore. The adhesion 
Se raiias G. P., Apple rots in Illinois. Univ. of Ill. Agr. Exp. Sta. Bull. o- 
bls. 10 
B SCHRENK and SPAULDING, The bitter rot of apples. U. S. Dept. Agr. 
we Plant Industry Bull. 44. pls. 9. 1903. 
= 
